Process of and apparatus for manufacturing tin-plate



(No Model.) 2Sheets'Sheet 1.

W. ROGERS. PROCESS OF AND APPARATUS FOR MANUFACTURING TIN PLATE.

Patented May 1'7 O O O O n HI IHNHH I IH WITNESSES MINGTON, n. cy

m: NORRIS a e Tans co. momu'mo. WAS

W. ROGERS. PROCESS OF AND APPARATUS FORMANUFAGTURINGATIN PLATE.

2 Sheets-Sheet; 2.

(No Model.)

Patented May 17 INVENTOR WITNESSES m: Noam: PEYERS 00.. Mmaumm vusummcmo. c.

NITED STATES PATENT FFICE.

WILLIAM ROGERS, OF LEEOHBURG, PENNSYLVANIA, ASSIGNOR OF ONE- I-IALF TOJAMES A. BEAVER, OF BELLEFONTE, PENNSYLVANIA.

PROCESS OF AND APPARATUS FOR MANUFACTURING TIN-PLATE.

SPECIFICATION forming part of Letters Patent No. 604,195, dated May 17,1898.

Application filed October 24, 1896. Serial No. 609,958. (No model.)

'9 all whom, it may concern.-

Be it known that I, WILLIAM ROGERS, of Leechburg, in the county ofArmstrong and State of Pennsylvania, have invented a new and usefulImprovement in Processes of and Apparatus for Manufacturing Tin-Plate,of which the following is a full, clear, and exact description,reference being had to the accompanying drawings, forming part of thisspecification, in which-- Figures 1 and 2 are vertical sections of theapparatus which I employ for containing the sheets of iron whensubjected to the process of annealing, decarbonizing, and deoxidizingthem preparatory to tinning. Fig. 3 is a vertical section of agrease-pot in which the annealed sheets are prepared for tinning. Fig.at is a vertical section of the tank for the melted tin and of theapparatus for suspending and dipping the sheets therein. Fig. 5 is avertical section of a smaller tin-pot for second tinning. Fig. 6 is averticalsection of apparatus for subjecting the tinned sheets to finaltreatment, rolling, and compression. In the several figures like lettersof refer-.

ence denote similar parts of my apparatus.

My improved process consists of two principal steps-411st, the annealingand purifying of the sheets from oxygen and carbon before tinning, and,second, the coating of the sheets with tin.

In the ordinary process of making tin-plate the sheets having beenhot-rolled to the desired size and thickness are first pickled inheatedsulfuric or hydrochloric acid to remove the surface oxid or scale, whichis called black pickling, and thenwashed several times in water toremove all trace of the acid. They are then placed in a closed iron boxand subjected to the heat of a furnace to anneal or soften them andgradually cooled out of access of the atmosphere. They are thencold-rolled between polished rolls to remove the roughness of thesurface caused by the formation and removal of surface oxid, which givesthem a close texture and a polished appearance. They are then againannealed in like manner as before, pickled, and washed, after which theyare ready for tinning. This second pickling is usually necessary toremove the oxid from the edges of the sheet and is injurious to thecentral part of the sheet from which the oxid has been removed by thefirst pickling.

In my process the preparing of the plates for tinning differsessentially from that just described, among others, in the followingimportant particulars: First, great care is taken to protect the sheetsafter they are rolled and during the annealing process from the actionof the oxygen of the atmosphere and to surround them with a substancewhich is neither carburizing nor oxidizing for the exclusion ofatmospheric air, so that the formation of further scale on the surfaceof the iron is prevented, and by the mutual reaction of the oxid on thesurface of the iron sheets and of the carbon contained in the body ofthe iron it may be both deoxidiz'ed and decarburized on exposure to theheat of the furnace. By this means the removal of the scale resultingfrom the exposure of the heated plates to the air during rolling isrendered not only unnecessary, but undesirable, and the roughness of thesheets caused by the formation of scale and its removal by acidtreatment is largely prevented. The body of the metal in the sheetsbeing thus purified by the complete decarbonization resulting from myprocess of annealing and by the reduction of any surface oxid the sheetsacquire a remarkable degree of softness and flexibility, indicating anunusual degree of freedom from either carbon or oxygen. By my process,therefore, I dispense with the black pickling in acid ordinarilypracticed after hot-rollin g, because the surface scale then formed isnot only removed by the annealing process, but serves.

a useful purpose in the annealing-chamber, and I also dispense with thecold-rolling ordinarily practiced after the first annealing, becausesuch rolling has the effect of compacting the iron, and if practiced inmy process would tend to destroy its porous condition resulting fromdecarbonization, and as a consequence I further dispense with the secondannealing of the sheets,'which is practiced in the usual method for thepurpose of removing the stiffness due to the cold-rolling.

The result of the porous texture given to the iron sheets by my methodof annealing is that the tin or other coating metal when in be rammed inplace.

a liquid condition enters the pores of the iron, forming a union moreresembling a chemical than a mechanical combination of the iron andcoating metal and is pressed into a very perfect union by the finalrolling, besides which the great freedom of the iron from the presenceof either carbon or oxygen gives it an extraordinary degree of softnessand flexibility.

In practicing my invention the sheets of iron having been firsthot-rolled in the usual way to the desired size and thickness areplaced, without previous removal of scale by pickling or otherwise, in apack of, say, five hundred to six hundred sheets, more or less, in anannealing-box so constructed as to permit of the sheets being easilyplaced therein and removed therefrom and at thesame time to permit ofthe use of means to exclude the admission of atmospheric air.

In the drawings, Figs. 1 and 2, I have shown twoconstructions ofannealing-box which I have devised for this purpose. Fig. 1 represents,partly in section, an annealing-box a, made, preferably, of cast-iron,though strong wrought-iron plates may be used in its ,construction orclay such as is used in the manufacture of glass-melting pots. This boxa isclosed at the top and at the sides, being made air-tight, and in useis set with the open bottom downward on a base-plate b, on which theopen end of the box rests. The baseplate is surrounded with a flange 0,so that pulverized material, sufficiently refractory to stand the heatof the furnace-such as pulverized-iron ore, sand, or dolomite-is placed,as-shown at d, so as to preventthe access of air into the box. Thesheets of iron or steel are placed in a pack on the base-plate b and arecovered by an envelop e, preferably of sheet-iron, which may be made inthe shape of a box, either in one part with an open bottom or in-twoparts fitting telescopically one over the other. placed over the envelope and is large enough to leave a space of about two inches on top andaround the inner box or envelop e, which covers the sheets, and in thisspace is introduced sand, pulverized iron ore, or dolomite, which willresist the action of the heat. This pulverized material is inserted intothe space around the sheets through small openings f in the top of theouterbox and may be rammed compactly by means of an iron rod. The

other construction of annealing-box is shown in Fig. 2, which representsa box a, of castiron orother suitable material, closed at bottom andopen at top, where it is inclosed by a covering-plate f. The sheets ofiron or steel are placed in a pack surrounded by a case or envelop 6',preferably of sheet-iron, which is covered over at the top to preventtheentrance of sand, iron ore, or dolomite placed within the outerannealing-box a and on'top and around the sides of the inner box e'to-athickness of about two inchesand may The purpose of this ar- The outerbox a is then scale or oxid on the sheets and the carbon contained inthe body of the iron may mutually react, forming carbon dioxid, whichescapes from the iron sheets. It may in some cases be found desirablewhere the amount of oxid on the surface of the iron is considerable toplace some sawdust or other carbonaceous matter around the bottom of thepile of sheets within the envelop e; but this I have found to beordinarily unnecessary, and as a general practice I prefer to introducenothing into the annealing-box around the sheets that will have anydecided chemical action thereon; but I have also found that iron ore(oxid) in a pulverized condition operates well and does not seem tohinder the deoxidation of the sheets. The annealing-box, with itscontents, is then placed in a reverberating or other suitable furnaceand is therein exposed to a suitable heatsay about 2,500 Fahrenheit-forabout ten hours, more or less, according to the size of theannealing-box and the amount of sheets of iron to be annealed.Preferably these annealing-boxes are removable from the furnace for thepurpose of charging them and of removing the contents. It is necessarythat the sheets when removed from the annealing-box should be cold or sonearly so as'not to be liable to the danger of oxidation of the surfaceof the metal when exposed to the air.

The sheets of iron should be allowed to become suificiently cold toprevent oxidation on exposure to the external air before their removalfrom the annealing-box. The result of annealing the sheets in the mannerdescribed is that they are of a dull silver-like or leaden appearanceand are when removed from the annealing-box very flexible, indicatingthat reaction between the oxid scale on the surface of the iron'and thecarbon contained in the body of the iron has resulted in the removal ofthe oxygen and carbon which were present on or in the sheets of ironbefore the annealing operation commenced.

If there should be any appearance of surface oxidation remaining on anyof the sheets when removed from the annealing-box such sheets should besubjected for a few minutes only to immersion in a bath of a weaksolution of muriatic or sulfuric acid in water, and then thoroughlywashed with alkaline water, such as lime-water, to remove any trace ofacid which would be injurious to the sheets.

Another advantage of the method of annealing the sheets which I havedescribed is that the effect on each sheet is very uniform, so thattheedges are deoxidized as thoroughly as other parts of the sheets, aresult difficult to attain by the ordinary methods.

IIO

After the sheets have been annealed and freed from scale, as described,and cool enough to prevent oxidation they are immersed in water forabout half an hour to wash off any particles of oxid which may yetremain adhering to their surface and are then ready for the tinningoperation without further rolling, the eifect of the annealing process,as before stated, being to leave the iron in a slightly porouscondition, so that the coating of tin takes a firmer hold on the surfaceof the plates.

In the process of tinning I employ the apparatus shown in Figs. 3, 4, 5,and 6. The sheets are first dipped in a pot of grease w, such as shownin Fig. 3, which may be of any desired construction, and therefore doesnot need any special description. The grease I prefer to use is tallow,which should be as free as possible from acid and which is kept in amelted condition by the frequent contact with the iron sheets, which arestill warm enough for the purpose; or if the grease used is of suchconsistency as to require it a furnace x may be placed under thegrease-pot it: with the side flues n n, as shown in Fig. 3} Thesesheets, with their coating of grease, are then placed one by one in avertical position in a rack j, (see Fig. 4,) which may hold anyconvenient number of plates, say from fifty to one hundred. This rack issuspended vertically over the tin-pot 7c from a small steamcylinder Zorother device, by which the rack, with its burden of iron plates, may berepeatedly and rapidly raised and lowered. The tinpot k is heated by afurnace m, placed underneath it, and hot-air flues 'n n at the sides, asshown in Fig. 4. The purpose of the rack j is not chieflythe convenienceof handling, but it also enables the sheets to be repeatedly and quicklydipped into the molten tin, the efiecti of which is that as the moltentin has a greater aflinity for oxygen than has the black plate (iron orsteel) at a temperature of about 450 Fahrenheit this fact, together withthe friction created between the melted tin and the surface of thesheet, aids in the removal therefrom of any particles of scale or oxidwhich may have been formed on their surface during the water-washingbefore mentioned. The tin in this pot or tank is should be kept at asnearly a constantly-uniform temperature of about 450 Fahrenheit aspossible, or at a heat sufficiently above the melting-point of thecoating metal, whatever it may be, to keep it in a perfectly liquidcondition, and the immersion of the sheets in the tin-bath should becontinued for about ten minutes. The sheets thus tinned are then removedfrom the rack j to another bath 0 of molten tin which is at atemperature somewhat-say about 25 Fahrenheit-lower than the tin in thetin-pot 76. This bath 0 may be of less width than the tin-pot k, asshown in the drawings, Fig. 5, because the sheets need not be held apartat this dipping as they are by the rack j. This bath 0 may be heated, asshown in the drawings, by a furnace y with side flues n 01. From thisbath 0 the tinned sheets are removed one by one to the greasepot 1),(see Fig. 6,) which is heated by a furnace q and side flues r r. Thisgrease-pot 19 contains grease, but, if desired, it may also containmolten tin if a third dipping in tin is deemed desirable. In thedrawings, Figs. 6, the tank is shown filled with molten tin up to theline 00 0c, and when this is the case the grease of course floats on thesurface of the molten metal. In order to prevent the grease being set onfire by the heat of the molten tin, it is kept comparatively cool bymeans of a set of horizontal pipes s 3, passed through the tank near toits upper edge, through which cold Water or air is caused to pass, andthen the grease is kept at a temperature of about 150 Fahrenheit. Intothis pot, Fig. 6, whether it be filled with grease alone or also withmelted tin, the sheets are immersed one by one in a vertical orsubstantially vertical direction and are immediately raised anddelivered out of the pot, the delivering-rolls forcibly compressing thetinned sheet and giving it a polished surface. by means of two pairs ofrolls, preferably, although one pair might suffice. The upper pair t tare made of polished steel, the lower pair preferably of copper. Theserolls are placed near the top of the grease-pot 19, so as to be immersedin the grease, and if tin is used in contact therewith, so that bothpairs of rolls shall be coated with tin. The rolls it u u of each pairare preferably geared together by cog-wheels located on their shaftsoutside of the grease-pot with an interposed idler-Wheel 1;, so as tosecure the requisite motion. Rotary motion is given to these rolls inany suitable manner, which may be con veniently efiected by means of apair of belts with fast and loose pulleys, so that the motion of therolls may be reversed as the sheets are alternately dipped into andraised out of the grease-pot. This third dipping into tin may bedispensed with, if desired, in which case grease only is placed in thepct 19.

- The rolls of the upper pairtt, or, if desired, also of the lower pairu u, are furnished with screws or other well-known device by which theycan be forced into close surface contact with each side of the tinnedsheet as it passes between them. The object of this pressure thusapplied to the delivering and finishing rolls is not only to lower andraise the sheets into and out of the pot and to give them a smoothsurface and finished appearance, but also and chiefly to cause the tinto penetrate the pores of the sheet which have been left open by reasonof the deoxidation and decarbonization, as before described, and by theabsence of rolling before tinning.

Instead of having separate furnaces 'm, q, to, and y under thegrease-pot and tin-pots, they may be so arranged as to be heated by aThis is eifected' common furnace, the degree of heat applied to each potor tank being regulated by means of dampers connected in the usual waywith the fines n n, surrounding each of these vessels.

In the above description I have spoken of my invention as applied to thepurpose of making tin-plate; but it is also applicable to themanufacture of terne-plate or sheet-iron covered with a mixture invarious proportions of tin and lead or of zinc or other metal which iscapable of being coated onto the surface of sheet metal.

My invention is also applicable to the manufacture of tin-plate fromrolled sheets of steel; but in this case it will be necessary tointroduce into the annealing-boxes some pulverized oxid in order todecarburize the steel plate, the proportion of which will depend uponthe percentage of carbon in the steel and of oxygen in the oxid; and Idesire it to be specially observed that sheets of steel decarburized andthen tinned in the manner I have described produce a very superiorquality of tin-plate.

By the terms iron and wrought-iron in the specification and claims asapplied to sheet-iron to be treated as described in this specification Irefer to sheet-iron substantially such as is produced by the ordinaryprocesses of manufacturing sheet-iron having the property ofmalleability and containing carbon in a less amount than either castironor steel.

I desire it to be understood that I do not claim, broadly, aspreparatory to the tinning of sheet metal subjecting the sheets to heatin a closed box and then cooling before exposure to the atmosphere; but

What I do claim as my invention, and desire to secure by Letters Patent,is

1. As a step in the process of coating sheets of iron or steel with tinor other coating metal or alloy, preparing the sheets by subjectingthem, after rolling and without previous pickling for removing thescale, to heat in a suitable furnace while inclosed in a pack in asuitable vessel or box, and protected from the access of atmospheric airby surrounding them with pulverized sand, lime, iron ore, or othersuitable material, whereby is effected a mutual reaction between theexternal oxid scale and the internal carbon of the sheets; substantiallyas and for the purpose described.

2. In the process of preparing sheet-iron for coating with tin or othermetal or alloy, deoxidizing and decarburizing the sheets without removalof the iron scale, by inclosing them in a pack within a suitablereceptacle, and preventing the access of atmospheric air by surroundingthem with sand orpulverized material, such as dolomite or iron ore,placed within the receptacle, the sheets being protected from actualcontact with such pulverthe sheets thus surrounded to heat in a suitablefurnace and thereby effecting a mutual reaction between the externaloxid (scale), and the internal carbon, of the sheets, substantially asdescribed.

3. The process of reducing the oxid and largely eliminating the carbonfrom sheets of rolled wrought-iron, at one operation, by subj ectin gthem, Without previous removal of the oxid coating, to furnace heat,when inclosed in a substantially air-tight receptacle, and protectedfrom access of external air, effecting thereby a mutual reaction betweenthe oxid of the external scale and theinternal carbon, of the sheets,substantially as described.

4:. As a finishing step in the process of manufacturing tin-plate, orother metal-coated sheets, subjecting thejsheets to the compressive andpolishing action of burnished steel rolls coated wholly or partiallywith grease, said sheets having been first treated, without removal ofthe surface oxid to a simultaneous deoxidizing and decarburizingoperation of heating in a substantially air-tight receptacle, and thencoated by dipping in molten metal substantially as described.

5. The process of making tin-plate or other metal-coated sheet-iron, bysubjecting the metal sheets to a process of simultaneous deoxidation anddecarburization, by exposure to heat in a suitable vessel protected fromaccess of external atmosphere for the purpose of effecting a mutualreaction between the external oxid (scale) and the internal carbon, ofthe sheets, then coating the wrought-iron sheets by dippingin tin,orother coating metal in a molten condition, and finally subjecting thesheets to the compressive action of polished steel rolls, to compact thepores of the metal sheet, and effect a firmer adherence of the coatingmetal, substantially as described.

6. The process of coating sheet-iron with tin or other metal or alloy,consisting in the following steps, viz: deoxidizing, decarburizing andsoftening the sheets in the manner hereinbefore described withoutprevious removal of the surface oxid, by subjecting them to heat in afurnace when inclosed in a substantially air-tight receptacle, protectedfrom access of external atmosphere, then coating such sheets with meltedgrease, then dipping the sheets repeatedly in a tank of melted coatingmetal, then dipping each sheet separately in a tank of melted metal at alower temperature, and finally subjecting sheets so prepared and coatedto rolling pressure while immersed in melted grease; substantially asdescribed.

7. The apparatus hcreinbefore described for finishing sheets ofwrought-iron after immersion in molten coating metal consisting of atank for holding grease, or grease and molten coating metal,means forheating said tank,

cooling-pipes horizontally traversing said ing and delivering themetal-coated sheets, tank to prevent the overheating of the grease,substantially as described. I0 said tank being furnished with one ormore In testimony whereof I have hereunto set pairs of rolls, one pairat least arranged to my hand.

5 be in contact with or immersed in grease, and WILLIAM ROGERS.

adapted to exert a compacting and polishing Witnesses: pressure on bothsurfaces of each coated sheet, J. D. ORR,

passing through between them, and for feed- J. B. KIFER.

. DISCLAIMER.

60 4 ,195.' William Rogers, Leechhurg, Pa, "Paoonss OF AND APPARATUS FORMANUFAC= TUBING TIN-PLATE. Patent dated May 17, 1898. Disclaimer filedJune 23, 1902, by the executor of said WI IAii ROGERS and the presentassignees.

Enter their disclaimer- To those parts of the specification which are inthe following Words:

On line 102 of the first page of the specification the Words or othercoating metal.

Page 4-, the 6th, 7th, 8th, 9th, 10th, 11th, 12th, and 13th lines, asfollows:

In the above description I have spoken of my invention as applied to thepurpose of making tin-plate but it is also applicable to the manufactureof terne-plate or sheetiron covered with a mixture in variousproportions of tin and lead or of zinc or other metal which is capableof being coated onto the surface of sheet metal. Claim 1, lines 2 and 3,the words or other coating metal or alloy. Claim 2, line 2, the Words orother metal or alloy. Claim 4, lines 2 and 3, the Words or othermetal-coated sheets. Claim 5, lines 1' and 2, the Words or othermetal-coated sheet-iron. Claim 5, line 10, the Words or other coatingmetal.

Claim 6, line 2, the words or other metal or alloy.[0fiicial Gazette,July 1, 1902.]

